firmware/2lib/2secdata_kernel.c

/* Copyright 2015 The Chromium OS Authors. All rights reserved.
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 *
 * Secure storage APIs - kernel version space
 */

#include "2common.h"
#include "2crc8.h"
#include "2misc.h"
#include "2secdata.h"
#include "2secdata_struct.h"
#include "2sysincludes.h"

vb2_error_t vb2api_secdata_kernel_check(struct vb2_context *ctx)
{
	struct vb2_secdata_kernel *sec =
		(struct vb2_secdata_kernel *)ctx->secdata_kernel;

	/* Verify CRC */
	if (sec->crc8 != vb2_crc8(sec, offsetof(struct vb2_secdata_kernel,
						crc8))) {
		VB2_DEBUG("secdata_kernel: bad CRC\n");
		return VB2_ERROR_SECDATA_KERNEL_CRC;
	}

	/* Verify version */
	if (sec->struct_version < VB2_SECDATA_KERNEL_VERSION) {
		VB2_DEBUG("secdata_firmware: version incompatible\n");
		return VB2_ERROR_SECDATA_KERNEL_VERSION;
	}

	/* Verify UID */
	if (sec->uid != VB2_SECDATA_KERNEL_UID) {
		VB2_DEBUG("secdata_kernel: bad UID\n");
		return VB2_ERROR_SECDATA_KERNEL_UID;
	}

	return VB2_SUCCESS;
}

uint32_t vb2api_secdata_kernel_create(struct vb2_context *ctx)
{
	struct vb2_secdata_kernel *sec =
		(struct vb2_secdata_kernel *)ctx->secdata_kernel;

	/* Clear the entire struct */
	memset(sec, 0, sizeof(*sec));

	/* Set to current version */
	sec->struct_version = VB2_SECDATA_KERNEL_VERSION;

	/* Set UID */
	sec->uid = VB2_SECDATA_KERNEL_UID;

	/* Calculate initial CRC */
	sec->crc8 = vb2_crc8(sec, offsetof(struct vb2_secdata_kernel, crc8));

	/* Mark as changed */
	ctx->flags |= VB2_CONTEXT_SECDATA_KERNEL_CHANGED;

	return sizeof(*sec);
}

vb2_error_t vb2_secdata_kernel_init(struct vb2_context *ctx)
{
	struct vb2_shared_data *sd = vb2_get_sd(ctx);
	vb2_error_t rv;

	rv = vb2api_secdata_kernel_check(ctx);
	if (rv)
		return rv;

	/* Set status flag */
	sd->status |= VB2_SD_STATUS_SECDATA_KERNEL_INIT;

	return VB2_SUCCESS;
}

uint32_t vb2_secdata_kernel_get(struct vb2_context *ctx,
				enum vb2_secdata_kernel_param param)
{
	struct vb2_shared_data *sd = vb2_get_sd(ctx);
	struct vb2_secdata_kernel *sec =
		(struct vb2_secdata_kernel *)ctx->secdata_kernel;
	const char *msg;

	if (!(sd->status & VB2_SD_STATUS_SECDATA_KERNEL_INIT)) {
		msg = "get before init";
		goto fail;
	}

	switch (param) {
	case VB2_SECDATA_KERNEL_VERSIONS:
		return sec->kernel_versions;

	default:
		msg = "invalid param";
	}

 fail:
	VB2_REC_OR_DIE(ctx, "%s\n", msg);
	return 0;
}

void vb2_secdata_kernel_set(struct vb2_context *ctx,
			    enum vb2_secdata_kernel_param param,
			    uint32_t value)
{
	struct vb2_shared_data *sd = vb2_get_sd(ctx);
	struct vb2_secdata_kernel *sec =
		(struct vb2_secdata_kernel *)ctx->secdata_kernel;
	const char *msg;

	if (!(sd->status & VB2_SD_STATUS_SECDATA_KERNEL_INIT)) {
		msg = "set before init";
		goto fail;
	}

	/* If not changing the value, just return early */
	if (value == vb2_secdata_kernel_get(ctx, param))
		return;

	switch (param) {
	case VB2_SECDATA_KERNEL_VERSIONS:
		VB2_DEBUG("secdata_kernel versions updated from %#x to %#x\n",
			  sec->kernel_versions, value);
		sec->kernel_versions = value;
		break;

	default:
		msg = "invalid param";
		goto fail;
	}

	/* Regenerate CRC */
	sec->crc8 = vb2_crc8(sec, offsetof(struct vb2_secdata_kernel, crc8));
	ctx->flags |= VB2_CONTEXT_SECDATA_KERNEL_CHANGED;
	return;

 fail:
	VB2_REC_OR_DIE(ctx, "%s\n", msg);
}